The most common and most likely answer to this crossword clue is the 4 letter word JURY
J
U
R
Y
Buddy explains!
The straight part
We know that "Improvise" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case improvise = jury.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does JURY mean?
JURY noun- A group of individuals chosen from the general population to hear and decide a case in a court of law.
- A group of judges in a competition.
- The audience attending the first night of a performance, whose reaction may determine whether it succeeds or fails.
- To judge by means of a jury.
- For temporary use; applied to a temporary contrivance.